Environ. Scl. Technol. 1985, 19, 716-720
Science (Washington, D.C.) 1978,202,515. (27) Pitts, J. N., Jr.; Lokensgard, D. M.; Ripley, P. S.; Van Cauwenberghe, K. A.; Van Vaeck, L.; Shaffer, S. D.; Thill, A. J.; Belser, W. L., Jr. Science (Washington, D.C.) 1980, 210,1347. Van Cauwenberghe, K.; Van Vaeck, L. “Advances in Mass Spectrometry”; Heyden & Son Ltd.: London, 1980; Vol. VIII, p 1499. Lane, D. A.; Katz, M. “Fate of Pollutants in the Air and Water Environments”;Wdey-Interscience: New York, 1977; Vol. 11, p 137. Lofroth, G.; Toftgard, R.; Carlstedt-Duke, J.; Gustaffson, J. A.; Brorstrom, E.; Grennfelt, P.; Lindskog, A. EPA’s Diesel Emissions Symposium, Raleigh, NC, 1981. Lundgren, D. A. J. Air Pollut. Control Assoc. 1967,17,225. Badger, G. M.; Buttery, R. G.; Kimber, R. W. L.; Lewis, G. E.; Mortiz, A. G.; Napier, I. M. J. Chem. SOC.1958,2449. Badger, G. M. “The Chemical Basis of Carcinogenic Activity”; Charles C. Thomas: Springfield, IL, 1962;p 16. Badger, G. M.; Donelly, J. K.; Spotswood, T. M. Aust. J. Chem. 1965,18,1249. Wynder, E. L.; Wright, G. P.; Lam, J. Cancer 1958,11,1140. Hoffmann, D.;Rathkamp, G.; Nesnow, S.; Wynder, E. L. J. Natl. Cancer Inst. (U.S.) 1972,45,1165. Kranz, Z.H.; Lamberton, J. A.; Murray, K. E.; Redcliffe, A. H. Aust. J. Chem. 1960,13,498. Douglas, A. G.; Eglinton, E. “Comparative Phytochemistry”;
Academic Press: New York, 1966;p 57. (39) Srivastava, D.N.; Bhatt, S. K.; Udupa, K. N. J. Am. Oil. Chem. SOC.1976,53,607. (40) Oro,J.; Nooner, D. W.; Wikstrom, S. A. Science (Washington, D.C.) 1965,148,870. (41) Eglinton, G.;Hamilton, R. J. “Chemical Plant Taxonomy”; Academic Press: London, 1963;p 187. (42) Kolattukudy, P. E. Phytochemistry 1975,6,963. (43) Caldicott, A. B.; Eglinton, G. “Phytochemistry”; Van Nostrand Reinhold: New York, 1973;Vol. 111, p 162. (44) Bray, E. E.; Evans, D. E. Geochim.Cosmochim. Acta 1961, 22,2. (45) Kollattukudy, P. E.; Walton, I. J. “Progress in Chemistry of Fats and Lipids”; Pergamon Press: Elmsford, NY, 1972; VOl. XIII, p 121. (46) Natusch, D. F. S.; Wallace, J. R. Science (Washington,D.C.) 1975,186,685. (47) De Wiest, F.; Della Fiorentina, H. Sci. Tot. Environ. 1977, 8,275. (48) Kertesz-Saringer, M.; Meszaros, E.; Varkonyi, R. Atmos. Environ. 1971,5, 249. (49) Miguel, A. H.; Friedlander, S. K. Atmos. Environ. 1978,12, 2407.
Received for review April 20,1983.Revised manuscript received March 1, 1985. Accepted March 13, 1985.
Calcium Chemistry and Deposition in Ionically Enriched Onondaga Lake, New Yorkt Steven W. EHler Upstate Freshwater Institute, Inc., Syracuse, New York 13214
Charles T. Drlscoll” Department of Civil Engineering, Syracuse University, Syracuse, New York 13210
rn The chemistry of aqueous calcium and the deposition of particulate calcium were studied in the epilimnion of calcium-polluted Onondaga Lake, NY, over a productive 7-month period. To evaluate calcium transformations, the water column was monitored for a number of pertinent water-quality parameters, and sediment traps were used to collect particulate material that settled from the epilimnion. Thermodynamic calculations indicate that the epilimnion of Onondaga Lake was oversaturated with respect t~ the solubility of CaC03 (pK, = 8.48) for the entire period of summer stratification. The extent of oversaturation with respect to the solubility of CaC03, and particulate calcium deposition, was significantly correlated with primary productivity. In-lake formation of CaC03 not only influences calcium transport but also appears to enhance the downward transport of phosphorus and organic carbon, and contributes to light attenuation.
Introduction Inorganic carbon generally constitutes the major pH buffering system in fresh waters. Calcium carbonate (CaCO,), most often as calcite, can also be an important particulate material in hard-water systems. The formation of calcite which results in the removal of aqueous Ca2+and dissolved inorganic carbon (DIC) represents a reactive adsorbent for potentially important interactions with f
Contribution No. 29 of Upstate Freshwater Institute, Inc.
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Table I. Morphometric Features of Onondaga Lake drainage basin area, km2 lake surface area, km2 lake volume, m3 mean depth, m maximum depth, m shoreline length, km hydraulic retention time, year
600
11.7 1.41 X lo8 12.0 20.5 17.9 0.25
phosphorus (1-3) and dissolved organic carbon ( 4 , 5 )and contributes to the attenuation of light in the water column (6, 7). A number of investigators ( 2 , 6 ,7-11)have evaluated the potential for CaC03 formation in hard-water lakes and have reported that these systems are often oversaturated with respect to the solubility of CaC03. This disequilibrium is apparently a result of both physicochemical (1, 6, 8, 12) and biochemical (2,7, 10, 11) factors. Conditions of maximum oversaturation with respect to the solubility of calcite (6, 7, 8-11) and in-lake formation (precipitation) of calcite are generally observed during the productive summer months. In this paper we describe temporal and vertical variations in the aqueous chemistry of calcium in the epilimnion of Onondaga Lake, NY, and the downward flux of particulate calcium from this layer, for a 7-month period of 1980. We discuss the interaction between transformations in solution chemistry and calcium deposition and the role of factors mediating these phenomena. Further, the potential importance of calcite formation and calcium de-
0013-936X/85/0919-0716$01,50/0
@ 1985 American Chemical Society
Table 11. Laboratory Chemical Analyses (29) ea2+ alkalinity (HCOc) Mg2+ Cl-
so>-
~ 0 ~ 3 -
titration, EDTA titration, HzSOd (pH of 4.3) titration, EDTA titration, Hg(NO& turbidimetric, BaSO, colorimetric, ascorbic acid
(dissolved reactive phosphorus) Fion selective electrode
position to selected lake processes is addressed.
Experimental Section Study Site. Onondaga Lake is located within metropolitan Syracuse, NY. The morphometric features of the lake are presented in Table I. The lake has a relatively short retention time, flushing an average of 4 times per year (13). Onondaga Lake has received domestic and industrial wastes from the metropolitan area during the last century of the region's development (14). In particular, waste from a chloralkali manufacturer (approximately 2.7 X lo6 kg day-') rich in Ca2+,Na+, and C1- has been discharged to the lake over the last 75 years. Onondaga Lake is also extremely productive (hypereutrophic; 14-16) as a result of high nutrient loadings. Manifestations of this condition include (1)extremely high rates of phytoplankton production (16), (2) high standing crops of algae (chlorophyll a levels are as high as 150 pg L-l (16), (3) low water transparency (Secchi disk transparency is frequently 8.1) shortly after spring turnover. In late June/early July pH values declined (7.5) throughout the period of summer stratification. Like calcium values, alkalinity generally increased with increasing lake depth (Figure IC).Epilimnetic alkalinity was highest shortly after spring turnover. Alkalinity generally was depleted from the upper waters from May through the end of September. A major exception to this trend coincided with an observed period of pH depression and resulted in the reintroduction of alkalinity to the upper mixed layer in late June (early July). In the autumn, as the thermocline migrated downward to the more saline lower waters, alkalinity values increased in the epilimnion. The upper waters of Onondaga Lake were generally oversaturated with respect to the solubility of calcite (SI > 0). Like pH, SI values were highest at the lake surface and declined with increasing depth. The degree of oversaturation with respect to calcite solubility was maximum in the upper waters early in the study period (May-July). This period of highly oversaturated conditions was interrupted in late June/early July by a marked decline in pH which resulted in a short period of lower SI values that were close to saturation (SI e 0). By mid-July SI values Environ. Sci. Technol., Vol. 19, No. 8, 1985
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I
$-
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-z
I
I
I
n n
I
020
E
0
0 15
t
gw
010
a
fY 3
005 0
1980
Flgure 2. Temporal variations In the downward flux of particulate calcium in Onondaga Lake during a portion of 1980.
Table 111. Calcite Saturation Index Values for Selected Lakes lake
3P
trophic state
ref
Cazenovia, NY Green Fayetteville, NY Jamesville, NY Erie Michigan
0.78
mestrophic
11
0.95 0.82 0.74 0.60
8 10 6 6
Ontario Saginaw Bay (Huron) Green Bay (Michigan) Zurich, Switzerland Onondaga, NY
0.78 1.30 1.29 1.04 1.10
oligotrophic mesotrophic mesotrophic oligo- and mesotropic mesotrophic eutrophic eutrophic
6 7 a
9
hypereutrophic
this work
Unpublished data from the first author.
E
.-c0
e
E
v)
TIME(rnonths) Flgure 1. Isopleths of (a) calcium, (b) pH, (c) alkalinity, and (d) calcite saturation Indexes (SI)for Onondaga Lake during a portion of 1980.
in the surface waters had increased to conditions that were highly oversaturated with respect to the solubility of CaCO,. In late summer/fall SI values declined but were still oversaturated with respect to calcite equilibrium. We also observed temporal variations in the downward flux of calcium to sediment traps placed at 10 m (Figure 2). Trends in calcium deposition were qualitatively consistent with our observed SI values. Calcium deposition was greatest early in the study period. The loss of calcium from the upper waters declined for a short period of time in late June/early July when pH and SI values declined. As pH and SI values increased following this event, calcium deposition also increased. Rates of calcium deposition generally declined for the balance of the study period. Discussion The concentrations of dissolved calcium in Onondaga Lake are atypically high as a result of the industrial loading, and therefore, substantial in-lake formation of particulate calcium is not unexpected. The progressive enrichment of calcium observed in the upper waters during our study reflects the continuous industrial loading of calcium coupled with the reduced flushing rate during the 718
maximum calcite SI
Environ. Scl. Technol., Vol. 19, No. 8, 1985
summer. Thus, because of the high external loading of calcium relative to vertical losses and simply the high calcium concentrations we did not observe the progressive depletion in calcium concentration that is typical of hard-water lakes that are oversaturated with respect to the solubility of CaC03 ( 1 0 , I I ) . Rather, the pronounced depletion of alkalinity in the epilimnion (Figure IC)is evidence for the massive decalcification of the lake. To facilitate a comparison of our observations with previous studies, we have tabulated values of maximum SI and trophic state reported for a number of lakes including Onondaga Lake (Table 111). Despite the elevated concentrations of dissolved calcium, the extent of oversaturation with respect to calcite solubility in Onondaga Lake was not high by comparison. A rather wide range of maximum SI values apparently occurs among different systems. These differences are probably largely due to ecosystem-specific differences in the rates of calcite formation that are affected by a number of processes within lake ecosystems. Factors such as the concentration and nature of dissolved organic matter, the availability of nucleation sites, and biological activity may affect the extent of oversaturation with respect to calcite solubility and rates of particulate calcium formation (6). Onondaga Lake is characterized by a high level of biological activity which serves to increase SI values. However, it also contains elevated concentrations of inorganic (24) and organic (16) particles which represent nucleation sites that may facilitate rates of particulate calcium formation. Variations in SI within Onondaga Lake were largely attributed to changes in pH (Figure 1). This trend has and been reported for other productive systems (7,!9-11) suggests that carbon dioxide metabolism can strongly influence calcium cycling in lakes. When photosynthetic
a
5
01
I
I
A
M
I
J
I
I
J A S T I M E (months)
A
I
J
i
O
N
Flgure 4. Temporal variatbn in gross primary productivity in Onondaga Lake during a portion of 1980.
M
J
J
A 19 80
S
0
N
Figure 3. Temporal variations In (a) temperate and (b) chlorophyll a in Onondaga Lake during a portion of 1980.
uptake exceeds input of COz,HzC03*(=(C0zlaq+ HzC03 ( I ) ) decreases and pH (and [C032-]) values increase, which result in increases in the SI (10, 11). Note that the solubility of calcite decreases as temperature increases ( I ) , and therefore, temperature changes may also contribute to variations in SI and in-lake formation of calcite (10). However, severd investigators (2, 7, 10, 11) have argued that COz metabolism (including photosynthesis) is the principal factor influencing particulate calcium formation in productive (mesotrophic to eutrophic) hard-water systems. Strong evidence in support of this argument is available from observations for Gull Lake, MI (25),where a substantial increase in productivity was documented over a 3-year period and from Saginaw Bay, Lake Huron (7), a system with pronounced spatial gradients in phytoplankton biomass. The annual rate of epilimnetic decalcification in Gull Lake increased as the rate of productivity increased (25). In Saginaw Bay the extent of calcite oversaturation was most pronounced in regions of high phytoplankton biomass, on an annual basis (7). Temperature and chlorophyll a (a measure of phytoplankton biomass) data for the upper 5 m of Onondaga Lake for the study period are presented in Figure 3. The changes in temperature (Figure 3a) we observed were typical of northern temperate lakes. Surface temperature increased to a maximum value (26 "C) in August and declined during the remainder of the season. The most prominent feature of the trends in chlorophyll a (Figure 3b) was a major decline from maximum concentrations in late June followed by an increase to a rather constant level in mid-July. The temporal changes in the calcite SI in the upper waters (0-5 m) appear to be consistent with the variations in chlorophyll a. Maximum SI values occurred during the chlorophyll a maximum in late May and early June (when temperatures were substantially less than the maximum value) and during the subsequent decline in late June. More importantly the perturbation in calcite SI values, from highly oversaturated values to conditions that were slightly oversaturated accompanied the major decline in chlorophyll a in late June. The nearly coincident 3 "C (19-16OC) decrease in temperature is also consistent with the observed reduction in SI; however, this temperature decrease can only account for a comparatively small (-0.5%) change in calcite solubility. Seasonal trends in SI were also consistent with the results of 53 productivity (gross) measurements made on days bracketing the sediment trap collections, by the
light/dark dissolved oxygen method (Figure 4). The short-term variations were a result of the variability in incident light, whereas the seasonal variations reflect changes in the level of primary productivity (16). Seasonal productivity was greatest during the period of maximum biomass in late May and most of June, lowest in late June and early fall, and at intermediate levels for the remainder of the study. Our observed values of areal primary productivity and calcite SI at 1- and 1-3-m depths were correlated (r = 0.55; p G0.05 and r = 0.44;p CO.1 for 1-and 1-3-m average SI values). The correlation deteriorated substantially as we included greater epilimnetic depths in this analysis. This depth dependency is probably due to a combination of two features of Onondaga Lake: (1) the low water transparency (17) and (2) the prevalent occurrence of secondary stratification in the epilimnion. Significant photosynthetic activity was limited to the upper 3 m of the water column throughout the study because of low transparency. The collection of particulate calcium in the sediment traps throughout the study was consistent with the continuous conditions of oversaturation with respect to calcite solubility that existed in the upper layers of the lake. Analyses of particles collected with sediment traps deployed in the same manner in 1981 with scanning electron microscopy, coupled with X-ray energy spectroscopy (24), and X-ray diffraction analysis of eurficial sediments collected during the study period, suggest that depositing calcium was largely a5 calcite. Significance of In-Lake Formation of Particulate Calcium. The precipitation and subsequent deposition of calcite is an important factor in the transport and cycling of materials in Onondaga Lake and probably other productive, hard-water lakes. The presence of calcite in the upper productive layers probably contributes to the large nonphytoplankton component of light attenuation reported for Onondaga Lake (17), thereby reducing the light available for photosynthesis. Effler et al. (26) have estimated that calcite was responsible for approximately 25 % of the overall attenuation observed in Onondaga Lake during the same time interval in 1978. A similar effect of calcite formation has been proposed for the Great Lakes (6). Calcite particles may also compete with phytoplankton for dissolved phosphorus. Thirty percent of the particulate phosphorus deposited during the period of this study was inorganic, probably largely coprecipitated with calcite (27). Substantial coprecipitation of phosphorus with calcite has recently been reported for another lake system (3) and has been demonstrated in laboratory simulations (28). The extremely high sedimentation rate (5-9 cmyear-l) reported for the lake has also been largely attributed to in-lake formation of particulate calcium (29). Wodka et al. (20 have hypothesized that calcite forms on the surface of phytoplankton in the productive layers of Onondaga Lake, Environ. Sci. Technoi., Vol. 19, No. 8, 1985
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increasing the overall density and thereby enhancing the rate of particulate deposition. This mechansm has obvious implications for the vertical transport of materials associated with phytoplankton (e.g., particulate phosphorus and organic carbon). Note that the high deposition of organic matter undoubtedly contributes to the rapid rate of hypolimnetic oxygen depletion that occurs in Onondaga Lake. Oxygen is depleted from the hypolimnion of the lake soon after the initiation of stratification in the spring (18).
Conclusions The epilimnion of calcium-enriched Onondaga Lake was oversaturated with respect to the solubility of CaC03 for the period of summer stratification. This condition resulted in in-lake formation of particulate calcium and decalcification of the upper mixed waters. The extent of oversaturation with respect to the solubility of CaC03 and particulate calcium deposition was significantly correlated to chlorophyll a and priniary productivity measurements. These observations suggest that biologically mediated changes in C 0 2result in fluctuations in solution pH and control the extent of particulate calcium formation. Calcite may serve as an adsorbent for the removal of PO, and DOC and may encrust particulate matter; both processes would facilitate the downward transport of nutrients. Registry No. Ca, 7440-70-2;CaC03, 471-34-1; C, 7440-44-0; calcite, 13397-26-7.
Literature Cited Stumm, W.; Morgan, J. J. “Aquatic Chemistry”; Wiley: New York, 1970. Otsuki, A.; Wetzel, R. G. Arch. Hydrobiol. 1974, 73,14-30. Murphy, T. P.; Hall, K. J.; Yesaki, I. Limnol. Oceanogr. 1983,28, 58-69.
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Effler, S. W.; Field, S. D.; Quirk, M. Freshwater Biol. 1982, 12,139-147.
Deffeyes, K. S. Limnol Oceanogr. 1965, 10, 412-420. Devan, S.; Effler, S. W. J . Environ. Eng. (N.Y) 1984,110, 93-109.
Effler, S. W.; Field, S. D.; Meyer, M. A.; Sze, P. J. Enuiron. Eng. Diu.(Am. Soc. Ciu. Eng.) 1981, 107, 191-210. Meyer, M. A.; Effler, S. W. Enuiron. Pollut. Ser. A 1980, 23, 131-152. Field, S. D.; Effler, S. W. J . Enuiron. Eng. (N.Y.)1983,109, 830-844. Field, S. D.; Effler, S. W. Arch. Hydrobiol. 1983,98,409-421. Wilcox, D. A.; Effler, S. W. Environ. Pollut. Ser. B 1981, 2, 203-215. Bloesch, J.; Burns, N. M. Schweiz. 2. Hydrol. 1980, 42, 15-55. Bloomquist, S.; Hakanson, L. Arch. Hydrobiol. 1981, 91, 101-132. American Public Health Association ”Standard Methods for Analysis of Water and Wastewater”, 14th ed.; American Public Health Association: Washington, DC, 1975. Westall, J. C.; Zachary, J. C.; Morel, F. M. M. “MINEQL,A Computer program for the Calculation of Chemical Equilibrium in Aqueous Systems”. Ralph M. Parsons Laboratory for Water Resources and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, 1976, Technical Note 18. Ball, J. W.; Nordstrom, D. K.; Jenne, E. A. “Additional and Revised Thermochemical Data for WATEQP: A Comuterized Model for Trace and Major Element Speciation and Mineral Equilibria of Natural Waters”. U.S.Geol. Survey Water Resources Investigations, Menlo Park, CA, 1980, Report 78-116. Yin, C.-Q.; Johnson, D. L. Limnol. Oceanogr. 1984, 29, 1193-1201. Moss, B.; Wetzel, R. G.; Lauff, G. H. Freshwater Biol. 1983, 10, 113-121. Effler, S. W.; Wodka, M. C.; Field, S. D. J. Enuiron. Eng. (N.Y) 1984,110, 1134-1145. Wodka, M. C.; Effler, S. W.; Driscoll, C. T. Limnol. Oceanogr., in press. Otsuki, A.; Wetzel, R. G. Limnol. Oceanogr. 1972, 17, 763-767. Effler, S. W.; Rand, M. C.; Tamayo, T. Water Air Soil Pollut. 1979, 12, 117-134. Received for review July 23, 1984. Revised manuscript received January 24, 1985. Accepted February 7, 1985.
